Asphalt paving advances available

Several of the key manufacturers are introducing new developments for the US asphalt paving market with vibration only screeds – Mike Woof writes
Asphalt milling, paving & compaction / June 24, 2024 1 minute 23 seconds Read
By MJ Woof
Caterpillar is now offering the novel screed plate system developed by Axenox

A number of new asphalt pavers for the North American market have been unveiled recently at the World of Asphalt event held in Nashville, TN. Organised by the US Association of Equipment Manufacturers (AEM), the show proved a major draw for the North American road construction industry.

Astec has upgraded its asphalt pavers, offering improved performance and servicability. The new F-Series version of the highway-class RP-175 benefits from a new frame and a simplified design. Power is from a Cummins B4.5 diesel that meets Tier 4 Final emissions requirements and delivers 130kW, with a revised cooling system that redirects heat away from the operator. The machine also has upgrades to its rubber track undercarriage that boost component life.

However, the key development is that the firm’s RP-175 and larger RP-195 are being made available with the sophisticated Smartedge technology, which can monitor the edge of the asphalt mat and move the screed edge automatically. The paver operator can set the overlap and the system will then track the edge of the paving mat, whether the machine is being driven in a straight line or round corners. The system uses a 600X laser that is said to be more accurate than other technologies and this package will be available at the end of 2024 once field testing is complete. It will only be for use on the F-Series machines however and cannot be retrofitted to earlier generation pavers from Astec or machines from other manufacturers.

This package is designed is for use in mainline paving operations and means that the screed operator can concentrate on ensuring the material supply is consistent, without having to keep adjusting the screed. The system was developed in-house and has been patented, while it can be used with machine control packages from all the major suppliers.

BOMAG’s CR1030T paver features a new front mount screed as well as an independent material supply system that allows the operator to run the augers or conveyor separately. The Versa 20 screed offers paving widths from 3-5.8m using hydraulic extension but allows up to 7m using bolt-on extensions. Berm-type screed extensions can also be fitted if required. The screed has three tubes to ensure stiffness, a feature taken from the firm’s proven European style screeds.

Operation is said to be easier due to the new HMI touchscreen console although dial controls have been retained for operators using gloves and the machine has Moba controls integrated into its systems. Power comes from a Cummins QSB6.7 diesel rated at 166kW and the machine runs on rubber tracks, with an automatic tensioning system to optimise wear life. 

Caterpillar is now offering an innovative three-dimensional screed plate system originally developed by Axenox. This follows a move by Caterpillar to buy the rights to the Axenox three-dimensional screed plates and the modular screed plate fastening system.

According to Nate Just, marketing manager for Cat Paving Products. “The innovative three-dimensional screed plate design improves mat density and smoothness as well as density at the joint to reduce compaction expense and improve the chances of achieving bonus. The modular fastening system reduces the time required to replace screed plates by more than 80% to lower costs and maximise paver uptime availability.”

Brothers Michael and Stuart Frost, long-time paving contractors and owners of Axenox developed this novel screed system to improve paving efficiency and quality. “Basic screed design had never changed in our lifetime or our father’s, so my brother and I developed our own screed. We knew we had something special with this technology,” said Stuart Frost.

The Axenox screed plate design has a three-dimensional, angular design instead of the conventional flat plates. This feature is said to deliver lateral compaction confinement to asphalt material. The kneading action helps aggregate to interlock efficiently, increasing mat and joint density along with improving mat smoothness.

Densities reaching 91% have been measured behind pavers equipped with the three-dimensional screed plates according to Caterpillar. These high densities can reduce the number of passes, lowering compaction cost. At the longitudinal joint, higher densities result in improved material containment during compaction to increase final density. Uniform mat temperatures gained by using the angular plates also help to reach specified densities more easily, helping contractors to meet bonus-level work.

The stiffer asphalt mat left behind the three-dimensional plates allow the breakdown roller to achieve higher densities before the mat reaches the tender zone. It produces a more stable unconfined edge that resists pushing and shoving by the breakdown roller, so consistent density readings are achieved across the entire mat width.

The three-dimensional cast plates are made with high strength chromium carbide, delivering high wear resistance. Whereas traditional screed plates are run with an elevated front angle of attack, increasing wear, grooves at the front of these plates act as the angle of attack, so they run flat to wear more uniformly and reduce cost.

A novel modular fastening system is also used to secure the plate to the screed, cutting plate change to less than four hours. After a one-time installation of the insulated conductor plate, simple screed plate changes are completed using a novel lock-and-go system. This eliminates the time-consuming process of removing asphalt material from the screed to access the nuts and bolts holding the plates in place. Once normal screed set-up and adjustments are completed on the conductor plate, minimal adjustments are required on future screed plate changes.

Dynapac has redesigned its D12C compact paver, boosting its performance and capabilites. A key development is the new remote control system that allows an operator to stand in the best position to view the paving process. The machine is optimised for use with Moba machine control technology and can also use the firm’s telematics package if required by a customer. Just 1m wide, the machine can operate in restricted space areas such as trenches and suits duties for reinstatement after utilities works, pavements, cycleways or driveways. A novel feature is that it can start paving from a 150mm milling cut. The machine offers paving widths from 1.2-3.5m and thicknesses of 200mm with its vibratory type screed. Power comes from a Tier 4 Final compliant Deutz diesel rated at 55kW but despite the machine’s compact size, its wide tracks help give it to the traction to be able to push a truck with a 30tonne GVW. The hopper wings can also unfold wide enough for the machine to be loaded by a larger tipper truck if necessary.

For the US market, the firm is also offering the D30W highway paver, a wheeled machine that can pave widths from 3.05-9.14m and thicknesses of 305mm. Power comes from an emissions-compliant Cummins QSB6.7 diesel rated at 168kW and the tractor weighs in at 15.3tonnes and 18.9tonnes when fitted with the Mat Master screed.

LeeBoy is still developing its electric paver although it is supplying one to a customer. Chris Broome, senior product manager for pavers at LeeBoy said, “The electric paver is out and putting down asphalt. The package is proven.”
The firm has built one of the units to order from a dealer and the spokesperson said, “We’re making some enhancements that should help the run time.”

The machine is aimed at use with local authorities and the spokesperson said, “Our target is with customers doing less than 300tonnes/day as they can do it on one charge.”

Unlike other electric pavers coming to market, the LeeBoy unit is said to be close in price to the standard diesel machine. Meanwhile it is also easy to charge and Broome said, “The machine can be charged at a conventional EV charging station. I had it charged up in 35-40 minutes and we’re compatible with all electric chargers.”

Meanwhile, the firm is also offering its 8680 paver with the option of the firm’s new LB7 screed, which weighs 3.2tonnes, in addition to the 2.3tonne LB5 screed available earlier. The heavy-duty LB7 offers paving widths from 2.44-4.7m and bolt-on options will be available in the future. The screed benefits from a new control unit, with powered extension height and powered angle of attack as well as a powered crown setting. A 14kW heating system is fitted to the main screed, with 3kW heating for the extensions, plus 1kW heating on each of the end gates. Power for the machine comes from a Kubota diesel rated at 156kW, while the machine has a 34kW generator with sufficient power to run the screed heating as well as units such as lighting balloons for night working.

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